You can calculate the effectiveness of your membrane by using a TDS Monitor.

STEP 1. Rinse the TDS Pocket Monitor with reverse osmosis water.

STEP 2. Test your Tap Water first with the TDS Pocket Monitor and key in the results below.

Tap Water Result:

STEP 3. Rinse the TDS Pocket Monitor with RO water again. Then test your RO water with your TDS monitor. Key in your results below. 

RO Water Result:


Membrane Effectiveness:


Now that we have the membrane’s rejection rate, what does this mean?

The rejection rate is the percentage of the amount of TDS (Total Dissolved Solids) eliminated from the tap water by the membrane. Example: A 90% rejection rate means that 90% of the TDS has been eliminated from the tap water.







If your Membrane Effectiveness is between 75-100% your membrane is operating within factory specifications.

If your Membrane Effectiveness is 74% or less then we recommend replacing your membrane and the flow restrictor as well as the pre and post filters.